Polymerization catalyst systems, their production and use

ABSTRACT

This invention is generally directed toward a supported catalyst system useful for polymerizing olefins. The method for supporting the catalyst of the invention provides for a supported bulky ligand transition metal catalyst which when utilized in a polymerization process substantially reduces the reactor fouling and sheeting in a gas, slurry or liquid pool polymerization process.

FIELD OF THE INVENTION

This invention relates to a method for the production of metallocenecatalyst systems, catalyst systems resulting from such method and theuse of such systems in olefin polymerization processes. The inventionparticularly relates to a method for preparing a supported metallocenecatalyst system which is particularly suitable for use in gas phase andslurry polymerization processes and which results in improved reactoroperability.

BACKGROUND OF THE INVENTION

It is widely known that olefin polymerization processes utilizing bulkyligand transition metal catalysts, otherwise known as metallocenecatalysts, have produced a diverse array of new polymers which areuseful in a wide variety of applications and products.

A well known problem associated with the use of metallocene catalystsystems is their tendency to cause fouling and/or sheeting in as phaseand slurry polymerization processes. Fouling on the walls of the reactorand/or reactor components results in many serious problems includingpoor heat transfer, particle morphology, and reactor shut-down.

In an effort to solve these problems, many catalyst system modificationsand modifications to the polymerization conditions have been reported.For example, U.S. Pat. Nos. 4,792,592; 4,808,667; 4,855,370; 4,876,320;4,978,722; 5,026,795; 5,034,481; 5,037,905 are all directed toward theuse of antistatic agents or other additives.

While these approaches may reduce fouling or sheeting somewhat, they arenot generally useful with all catalyst systems, they may be expensive toemploy, and they may not reduce both fouling and sheeting to a levelsufficient for the successful operation of a continuous process,particularly a commercial or large-scale process. Thus, it would behighly advantageous to have an improved metallocene catalyst system thatin a polymerization process would significantly enhance reactoroperability by reducing both fouling and sheeting.

SUMMARY OF THE INVENTION

This invention is generally directed towards a method for themanufacture of supported metallocene catalyst systems to catalystsystems resulting from such methods and to the use of such catalystsystems in polymerization processes.

In one embodiment an improved method is provided to produce a supportedbulky ligand transition metal catalyst system by contacting a poroussupport with a reaction product of a metallocene catalyst component, analumoxane and a surface modifier, where the metallocene catalystcomponent is a chiral, Group 4, 5 or 6 transition metal, bridged,substitute bisindenyl.

In yet another embodiment of the invention, there is provided a processfor producing propylene polyolefins by contacting propylene monomer,optionally with a comonomer in the presence of the catalyst systemdescribed above.

DETAILED DESCRIPTION OF THE INVENTION

Introduction

This invention is generally directed toward a supported catalyst systemuseful for polymerizing olefins. The method for forming the catalystsystem of the invention results in a useful polymerization catalystexhibiting improved reactor operability. The catalyst system of theinvention not only reduces fouling and sheeting in a gas phase, slurryor liquid polymerization process but the catalyst system has better flowproperties important to feeding the catalyst into the reactor. Also, thecatalyst system of this invention results in a high bulk density polymerproduct having improved physical properties. Further, it has beendiscovered that the use of a surface modifier in the method of theinvention protects the catalyst from direct or substantial reaction withscavenging components typically used to remove impurities. Thesescavengers can interact with the components of the catalyst system todecrease catalyst activity and reactor operability.

Making the catalyst of the invention as described above results in asimple, commercially useful and cost effective supported catalyst systemwhich exhibits a reduced tendency to cause sheeting or fouling duringthe polymerization of propylene polymers or copolymers without asignificant reduction in catalytic activity.

Metallocene Catalyst Components

The metallocene components employed in the present invention comprise aGroup 4, 5, or 6 transition metal, biscyclopentadienyl derivatives,preferably bisindenyl metallocene components having the followinggeneral structure: ##STR1## wherein M¹ is a metal of Group 4, 5, or 6 ofthe Periodic Table, for example titanium, zirconium, hafnium, vanadium,niobium, tantalum, chromium, molybdenum and tungsten, preferably,zirconium, hafnium and titanium, most preferably zirconium;

R¹ and R² are identical or different, are one of a hydrogen atom, a C₁-C₁₀ alkyl group, preferably a C₁ -C₃ alkyl group, a C₁ -C₁₀ alkoxygroup, preferably a C₁ -C₃ alkoxy group, a C₆ -C₁₀ aryl group,preferably a C₆ -C₈ aryl group, a C₆ -C₁₀ aryloxy group, preferably a C₆-C₈ aryloxy group, a C₂ -C₁₀ alkenyl group, preferably a C₂ -C₄ alkenylgroup, a C₇ -C₄₀ arylalkyl group, preferably a C₇ -C₁₀ arylalkyl group,a C₇ -C₄₀ alkylaryl group, preferably a C₇ -C₁₂ alkylaryl group, a C₈-C₄₀ arylalkenyl group, preferably a C₈ -C₁₂ arylalkenyl group, or ahalogen atom, preferably chlorine;

R³ and R⁴ are hydrogen atoms;

R⁵ and R⁶ are identical or different, preferably identical, are one of ahalogen atom, preferably a fluorine, chlorine or bromine atom , a C₁-C₁₀ alkyl group, preferably a C₁ -C₄ alkyl group, which may behalogenated, a C₆ -C₁₀ aryl group, which may be halogenated, preferablya C₆ -C₈ aryl group, a C₂ -C₁₀ alkenyl group, preferably a C₂ -C₄alkenyl group, a C₇ -C₄₀ arylalkyl group, preferably a C₇ -C₁₀ arylalkylgroup, a C₇ -C₄₀ alkylaryl group, preferably a C₇ -C₁₂ alkylaryl group,a C₈ -C₄₀ arylalkenyl group, preferably a C₈ -C₁₂ arylalkenyl group, a--NR₂ ¹⁵, --SR¹⁵, --OR¹⁵, --OSiR₃ ¹⁵ or --PR₂ ¹⁵ radical, wherein R¹⁵ isone of a halogen atom, preferably a chlorine atom, a C₁ -C₁₀ alkylgroup, preferably a C₁ -C₃ alkyl group, or a C₆ -C₁₀ aryl group,preferably a C₆ -C₉ aryl group; ##STR2## ═BR¹¹, ═AlR¹¹, --Ge--, --Sn--,--O--, --S--, ═SO, ═SO₂, ═NR¹¹, ═CO, ═PR¹¹, or ═P(O)R¹¹ ;

wherein: R¹¹, R¹² and R¹³ are identical or different and are a hydrogenatom, a halogen atom, a C₁ -C₂₀ alkyl group, preferably a C₁ -C₁₀ alkylgroup, a C₁ -C₂₀ fluoroalkyl group, preferably a C₁ -C₁₀ fluoroalkylgroup, a C₆ -C₃₀ aryl group, preferably a C₆ -C₂₀ aryl group, a C₆ -C₃₀fluoroaryl group, preferably a C₆ -C₂₀ fluoroaryl group, a C₁ -C₂₀alkoxy group, preferably a C₁ -C₁₀ alkoxy group, a C₂ -C₂₀ alkenylgroup, preferably a C₂ -C₁₀ alkenyl group, a C₇ -C₄₀ arylalkyl group,preferably a C₇ -C₂₀ arylalkyl group, a C₈ -C₄₀ arylalkenyl group,preferably a C₈ -C₂₂ arylalkenyl group, a C₇ -C₄₀ alkylaryl group,preferably a C₇ -C₂₀ alkylaryl group or R¹¹ and R¹², or R¹¹ and R¹³,together with the atoms binding them, can form ring systems;

M² is silicon, germanium or tin, preferably silicon or germanium, mostpreferably silicon;

R⁸ and R⁹ are identical or different and have the meanings stated forR¹¹ ;

m and n are identical or different and are zero, 1 or 2, preferably zeroor 1, m plus n being zero, 1 or 2, preferably zero or 1; and

the radicals R¹⁰ are identical or different and have the meanings statedfor R¹¹, R¹² and R¹³. Two adjacent R¹⁰ radicals can be joined togetherto form a ring system, preferably a ring system containing from about4-6 carbon atoms.

Alkyl refers to straight or branched chain substituents. Halogen(halogenated) is fluorine, chlorine, bromine or iodine atoms, preferablyfluorine or chlorine.

Particularly preferred metallocenes are compounds of the structures:##STR3##

wherein:

M¹ is Zr or Hf, R¹ and R² are methyl or chlorine, an R⁵, R⁶ , R⁸, R⁹,R¹⁰, R¹¹ and R¹² have the above-mentioned meanings.

The chiral metallocenes are used as a racemate for the preparation ofhighly isotactic polypropylene copolymers.

It is also possible to use the pure R or S form. An optically activepolymer can be prepared with these pure stereoisomeric forms. It ispreferred that the meso form of the metallocenes be removed to ensurethe center (i.e., the metal atom) provides stereoregular polymerization.

Separation of the stereoisomers can be accomplished by known literaturetechniques. For special products it is also possible to use rac/mesomixtures.

Generally, the metallocenes are prepared by a multi-step processinvolving repeated deprotonations/metallations of the aromatic ligandsand introduction of the bridge and the central atom by their halogenderivatives. The following reaction scheme illustrates this genericapproach: ##STR4##

The reader is referred to the Journal of Organometallic Chem., volume288 (1985), pages 63-67, and EP-A-320762, for preparation of themetallocenes described, both references are herein fully incorporated byreference.

Illustrative but non-limiting examples of metallocene include:Dimethylsilandiylbis(2-methyl-4-phenyl-1-indenyl)ZrCl₂Dimethylsilandiylbis(2-methyl-4,5-benzoindenyl)ZrCl₂ ;Dimethylsilandiylbis(2-methyl-4,6-diisopropylindenyl)ZrCl₂ ;Dimethylsilandiylbis(2-ethyl-4-phenyl-1-indenyl)ZrCl₂ ;Phenyl(Methyl)silandiylbis(2-methyl-4-phenyl-1-indenyl)ZrCl₂,Dimethylsilandiylbis(2-methyl-4-(1-naphthyl)-1-indenyl)ZrCl₂,Dimethylsilandiylbis(2-methyl-4-(2-naphthyl)-1-indenyl)ZrCl₂,Dimethylsilandiylbis(2-methyl-4,5-diisopropyl-1-indenyl)ZrCl₂,Dimethylsilandiylbis(2,4,6-trimethyl-1-indenyl)ZrCl₂,Phenyl(Methyl)silandiylbis(2-methyl-4,6-diisopropyl-1-indenyl)ZrCl₂,1,2-Ethandiylbis(2-methyl-4,6-diisopropyl-1-indenyl)ZrCl₂,1,2-Butandiylbis(2-methyl-4,6-diisopropyl-1-indenyl)ZrCl₂,Dimethylsilandiylbis(2-methyl-4-ethyl-1-indenyl)ZrCl₂,Dimethylsilandiylbis(2-methyl-4-isopropyl-1-indenyl)ZrCl₂,Dimethylsilandiylbis(2-methyl-4-t-butyl-1-indenyl)ZrCl₂,Phenyl(Methyl)silandiylbis(2-methyl-4-isopropyl-1-indenyl)ZrCl₂,Dimethylsilandiylbis(2-ethyl-4-methyl-1-indenyl)ZrCl₂,Dimethylsilandiylbis(2,4-dimethyl-1-indenyl)ZrCl₂,Dimethylsilandiylbis(2-methyl-4-ethyl-1-indenyl)ZrCl₂,Dimethylsilandiylbis(2-methyl-α-acenaphth-1-indenyl)ZrCl₂,Phenyl(Methyl)silandiylbis(2-methyl-4,5-benzo-1-indenyl)ZrCl₂,Phenyl(Methyl)silandiylbis(2-methyl-4,5-(methylbenzo)-1-indenyl)ZrCl₂,Phenyl(Methyl)silandiylbis(2-methyl-4,5-(tetramethylbenzo)-1-indenyl)ZrCl₂,Phenyl(Methyl)silandiylbis(2-methyl-a-acenaphth-1-indenyl)ZrCl₂,1,2-Ethandiylbis(2-methyl-4,5-benzo-1-indenyl)ZrCl₂,1,2-Butandiylbis(2-methyl-4,5-benzo-1-indenyl)ZrCl₂,Dimethylsilandiylbis(2-methyl-4,5-benzo-1-indenyl)ZrCl₂,1,2-Ethandiylbis(2,4,7-trimethyl-1-indenyl)ZrCl₂,Dimethylsilandiylbis(2-methyl-1-indenyl)ZrCl₂,1,2-Ethandiylbis(2-methyl-1-indenyl)ZrCl₂,Phenyl(Methyl)silandiylbis(2-methyl-1-indenyl)ZrCl₂,Diphenylsilandiylbis(2-methyl-1-indenyl)ZrCl₂,1,2-Butandiylbis(2-methyl-1-indenyl)ZrCl₂,Dimethylsilandiylbis(2-ethyl-1-indenyl)ZrCl₂,Dimethylsilandiylbis(2-methyl-5-isobutyl-1-indenyl)ZrCl₂,Phenyl(Methyl)silandiylbis(2-methyl-5-isobutyl-1-indenyl)ZrCl₂,Dimethylsilandiylbis(2-methyl-5-t-butyl-1-indenyl)ZrCl₂,Dimethylsilandiylbis(2,5,6-trimethyl-1-indenyl)ZrCl₂, and the like.

The metallocene catalyst components of this invention are described indetail in U.S. Pat. Nos. 5,149,819, 5,243,001, 5,239,022, 5,296,434 and5,276,208 all of which are herein fully incorporated by reference.

Activator Components

The activator or cocatalyst component of the present invention isalumoxane.

Generally, the alkylalumoxanes preferred for use in olefinpolymerization contain about 4 to 20 of the repeating units: ##STR5##where R is a C₁ -C₈ alkyl including mixed alkys. Particularly preferredare the compounds where R is methyl. There are a variety of methods forpreparing alumoxane, non-limiting examples of which are described inU.S. Pat. No. 4,665,208, 4,952,540, 5,091,352, 5,206,199, 5,204,419,4,874,734, 4,924,018, 4,908,463, 4,968,827, 5,308,815, 5,329,032,5,248,801, 5,235,081, 5,157,137, 5,103,031 and EP-A-0 561 476, EP-B1-0279 586, EP-A-0 594-218 and WO 94/10180, each of which is fullyincorporated herein by reference.

Some methylalumoxane (MAO) solutions tend to become cloudy andgelatinous over time. It may be advantageous to clarify such solutionsprior to use. A number of methods may be used to create gel-free MAOsolutions or to remove gels from the solutions. Gelled solutions areoften simply shaken or decanted. U.S. Pat. No. 5,157,137 discloses aprocess for forming clear, gel-free solutions of alkylalumoxane bytreating a solution of alkylalumoxane with an anhydrous salt and/orhydride of an alkali or alkaline earth metal.

Support Mediums

For purposes of this patent specification the terms "carrier" or"support" are interchangeable and can be any support material,preferably a porous support material, such as for example, talc,inorganic oxides, inorganic chlorides, for example magnesium chlorideand resinous support material such as polystyrene or polystyrene-divinylbenzene, polyolefins or polymeric compounds or any other organic supportmaterial and the like, or mixtures thereof.

The preferred support materials are inorganic oxide materials, whichinclude those of Groups 2, 3, 4, 5, 13 or 14 metal oxides. In apreferred embodiment, the catalyst support materials include silica,alumina, silica-alumina, and mixtures thereof. Other inorganic oxidesthat may be employed either alone or in combination with the silica,alumina or silica-alumina are magnesia, titania, zirconia, and the like.

Preferably, the support has a surface area in the range of from about 10to about 700 m² /g, a pore volume in the range of from about 0.1 toabout 4.0 cc/g and an average particle size in the range of from about10 to about 500 μm. More preferably, the support surface area is in therange of from about 50 to about 500 m² /g, the pore volume is in therange of from about 0.5 to about 3.5 cc/g and the average particle sizeis in the range of from about 20 to about 200 μm. Most preferably thesurface area range is from about 100 to about 400 m² /g, the pore volumeis from about 0.8 to about 3.0 cc/g and the average particle size isfrom about 10 to about 100 μm. The pore size of the carrier of theinvention is preferably in the range of from about 10 to about 1000° A,preferably from about 50 to about 500° A, and most preferably from about75 to about 350° A.

Surface Modifiers

The term "surface modifier" is defined herein to mean any compoundcontaining at least one electron rich heteroatom from Group IV, V and/orVI and a hydrocarbyl or substituted hydrocarbyl moiety. Typicalheteroatoms are silicon, oxygen, nitrogen, phosphorus, and sulfur. Thesurface modifier preferably also contains at least one active hydrogenatom attached to the heteroatom. The hydrocarbyl moiety should have amolecular weight such that it is soluble in typical hydrocarbonsolvents. The surface modifier may be represented by the formula, R_(m)XH_(n). R may be a branched or straight chain hydrocarbyl group orsubstituted hydrocarbyl group or groups having one or more carbon atoms.X is at least one heteroatom, which may be O, N, P or S or a combinationthereof; H is an active hydrogen; and n is such that the compound has nonet charge.

Non-limiting examples of the following general structures with R beingthe hydrocarbyl groups are: RNH₂, R₂ NH, (R'C(OH)_(n) R")NH₂,(R'C(OH)_(n) R")₂ NH, RCONH₂, RCONHR, RN(ROH)₂, RCO₂ H, RC(O)NROH,RC(S)OH, and R₂ PO₂ H. These compounds include amines, alcohols,phenols, thiols, silanols, diols, acids, and ethers.

In another embodiment the surface modifier may be expressed by theformula: ##STR6## where R³ is hydrogen or a branched or preferably astraight chain alkyl group having 1 to 50 carbon atoms. R¹ and R² may bethe same or different and may be the same as R³ or contain anotherheteroatom such as O, N, P or S.

In another embodiment, the surface modifier is represented by thefollowing formula for an alkoxylated tertiary amine: ##STR7## where R¹may be hydrogen or a (linear or branched) alkyl group of from 1 to 50carbon atoms; R² may be a hydroxy group such a (CH₂)_(x) OH radicalwhere x is an integer from 1 to 50, preferably 2 to 25. Non-limitingexamples include Kemamine AS-990 (available from Witco ChemicalCorporation, Houston, Tex.) having the formula C₁₈ H₃₇ N(CH₂ CH₂ OH)₂and Kemamine AS-650 (also available from Witco) having the formula C₁₂H₂₅ N(CH₂ CH₂ OH)₂. Other surface modifiers may includebishydroxyethylcocoamine, 2,2-(octadecylamino)bis ethanol,polyoxyethylene alkylamine, butyl stearate, glycerol and SPAN-80(available from ICI Specialties, Wilmington, Del.) having the formula:(CH₃)(CH₂)₇ CHCH(CH₂)₇ OCOCH₂ (CHOH)₄ CH₂ OH (sorbitan mono-oleate).

Quaternary ammonium compounds, hydrocarbyl sulfates or phosphates canalso be used as surface modifiers. Tertiary amines, ethoxylate aminesand polyether compounds are preferable surface modifiers.

Methods of Producing the Catalyst Systems

The catalyst system of the invention can be made in a variety ofdifferent ways. Preferably the metallocene catalyst component andactivator are combined to form a solution, which is then added to thecarrier, followed by the addition of the surface modifier. In anotherembodiment, the metallocene component and activator solution are addedto the carrier or vice-versa, the latter being preferred, then theresulting mixture, typically a slurry, is dried, optionally washed andre-dried, and then the surface modifier is added. In another embodimentthe surface modifier is added to a metallocene and/or activator solutiondirectly as a solid or liquid, and then the solution combined with thecarrier.

In another embodiment the surface modifier is dry blended with asupported metallocene catalyst system formed by combining the carrierwith the metallocene/alumoxane reaction product.

Optionally, the supported catalyst system is prepolymerized eitherbefore or after, preferably before, application of the surface modifierto the supported catalyst system.

In the preferred embodiment the metallocene catalyst component istypically slurried in a liquid to form a metallocene solution and aseparate solution is formed containing an activator and a liquid. Theliquid can be any compatible solvent or other liquid capable of forminga solution or the like with at least one metallocene catalyst componentand/or at least one activator. In the preferred embodiment the liquid isa cyclic aliphatic or aromatic hydrocarbon, most preferably toluene. Themetallocene and activator solutions are then mixed together and added toa porous support such that the total volume of the metallocene solutionand the activator solution or the metallocene and activator solution isless than four times the pore volume of the porous support, morepreferably less than three times, even more preferably less than twotimes, and most preferably in the range of about 0.8 to about 3 times,preferably about 0.9 to about 1.5 times and most preferably in the rangeof about 0.9 to about 1.25 times. The surface modifier may be added atany stage during this preferred method of making the catalyst system. Inthe most preferred embodiment, however, the surface modifier is addedafter.

The weight percent of the surface modifier based on the total weight ofthe catalyst system is in the range of from about 0.2 to about 5 weightpercent, more preferably from about 0.25 to about 3.5 weight percent andmost preferably from about 0.3 to about 3.5 weight percent.

The procedure for measuring the total pore volume of a porous support iswell known in the art. Details of one of these procedures is discussedin Volume 1, Experimental Methods in Catalytic Research (Academic Press,1968) (specifically see pages 67-96). This preferred procedure involvesthe use of a classical BET apparatus for nitrogen absorption. Anothermethod well know in the art is described in Innes, Total porosity andParticle Density of Fluid Catalysts By Liquid Titration, Vol. 28, No. 3,Analytical Chemistry 332-334 (March, 1956).

The general support technique employed involves contacting, in asuitable solvent or other liquid, a metallocene catalyst component asdescribed above with alumoxane or methylalumoxane (MAO) to form asoluble reaction product. The soluble reaction product is then contactedwith a porous carrier, wherein the total volume of the soluble reactionproduct added to the carrier is less than four times the pore volume ofthe carrier. The resulting supported catalyst system can be dried toensure that essentially all or most of the residual solvent is removedfrom the pores of the carrier before or after the introduction of asurface modifier. A free flowing supported catalyst system is therebyobtained.

In one embodiment, a method to produce a free flowing, optionallyprepolymerized supported catalyst system is provided, the methodcomprising the steps of: a) forming in a suitable solvent, ametallocene/alumoxane mixture wherein the metallocene is as describedabove; b) contacting the mixture of (a) with a porous carrier; whereinthe total volume of the mixture to the porous carrier is less than fourtimes the pore volume of the carrier; c) removing essentially all thesolvent; d) introducing a surface modifier; e) obtaining a supportedcatalyst system; and f) optionally prepolymerizing said supportedcatalyst system with one or more olefinic monomer(s), to form aprepolymerized supported catalyst system. This supported catalyst systemis useful for the production of polymers of propylene or copolymersthereof, having a molecular weight of about 50,000 or greater,preferably 100,000 or greater, a melting point of about 125° C. orgreater, preferably about 135° C. or greater, and more preferably about145° C. or greater and a bulk density of about 0.30 g/cm³ or greater.The resulting granular polymer also has a preferred average particlesize of about 300 to about 1000 microns or greater.

The catalyst system of the invention can be dried and still contain anamount of solvent, for example, toluene, in its dried state, however, itis preferred that substantially all the solvent is removed. For thepurposes of this patent specification and appended claims the term"substantially all of the solvent is removed" means that greater thanabout 90% of all the solvent is removed from the supported catalystsystem when drying.

In another embodiment of the invention, the mole ratio of the metal ofthe alumoxane component to the transition metal of the metallocenecomponent is in the range of ratios between 10:1 to 800:1, preferably20:1 to less than 500:1, and most preferably 50:1 to less than 400:1.

Polymerization Process of the Invention

The catalyst system of this invention is suited for the polymerizationof monomers and optionally comonomers in any polymerization orprepolymerization process, gas, slurry or solution phase; even a highpressure autoclave process can be utilized. In the preferred embodimenta gas phase or slurry phase process is utilized, most preferably a bulkliquid propylene polymerization process.

In the preferred embodiment, this invention is directed toward bulkliquid propylene slurry or gas phase polymerization or copolymerizationreactions involving the polymerization of propylene with one or more ofthe alpha-olefin monomers having from 4 to 20 carbon atoms, preferably4-12 carbon atoms, for example alpha-olefin comonomers of ethylene,butene-1, pentene-1, 4-methylpentene-1, hexene-1, octene-1, decene-1,and cyclic olefins such as styrene. Other monomers can include polarvinyl, diolefins such as dienes, norbornene, acetylene and aldehydemonomers.

In one preferred embodiment, the process of the invention is carried outin the absence of or in an reactor environment that is essentially freeof a scavenger material such as alkyaluminum compounds, for example,triethylaluminum, trimethylaluminum and isobutylaluminum. For thepurposes of this patent specification and appended claims the term"essentially free" means that less than 100 ppm by weight of scavengeris present in the reactor at any given point in time duringpolymerization.

EXAMPLES

In order to provide a better understanding of the present inventionincluding representative advantages and limitation thereof, thefollowing examples are offered.

EXAMPLE 1

PREPARATION OF CATALYST A

To a two gallon (7.6 liter) reactor previously flushed with N₂ was added3900 mL of methylalumoxane (MAO) in toluene (available from WitcoChemical Company, Houston, Tex., 10 wt % MAO solution) followed by 9.0 gof dimethylsilylbis(2-methyl-4,5-benzo-indenyl)zirconium dichloridedissolved in an additional 350 mL of MAO. The combined solutions werestirred for 10 minutes. As stirring continued, 400 g of silica (DavisonGrade MS948 FF, previously dehydrated to 800° C. under flowing N₂,available from W. R. Grace, Davison Chemical Division, Baltimore, Md.)was added over 10 minutes. The toluene was removed under a slow N₂ purgewhile raising temperature and vacuum to 68° C. and 25 in. (64 cm) of Hgto give a free flowing solid. The catalyst solid was washed four timeswith 5-7 liters of hexane each and the final wash decanted. After asecond drying as above 560 g of a free flowing solid was obtained. 250 gof the catalyst was charged to the reactor previously loaded with 4liters of hexane and 5 mL of a 25 wt % solution of triisobutylaluminumin hexane (available from Witco). Under stirring the slurry was cooledto 1-2° C. and cylinder containing ethylene and hydrogen (3 mol % H₂,Matheson Gas Products) was connected to the reactor. The gas was addedto the vapor phase at a flow rate of 0.08-0.17 cubic feet per minute(38-80 cubic cm per second) to control the slurry temperature to lessthan about 5° C. After 90 minutes N₂ as used to purge the excessethylene and hydrogen. The prepolymerized catalyst slurry was washedfour times with 5-7 liters of hexane each and the final wash decanted.After drying under vacuum solid catalyst A was recovered.

POLYMERIZATION

All the catalysts prepared were polymerized in accordance with thefollowing procedure. A 2 liter autoclave reactor previously flushed withN₂ and containing triethylaluminum (0.5 mL of a 1M solution in hexane)and 1000 mL of propylene was heated to a temperature of 74° C. Thecatalyst sample was slurried in 2 mL of hexane. The catalyst was chargedto the reactor with a flush of 250 mL propylene to start the reaction.After one hour the reactor was cooled, vented and purged with N₂ for 20minutes and then opened. The condition of the polymer and fouling levelof the reactor was noted. After removal from the reactor, the polymerwas dried for a minimum of 2 hours at 75° C. in vacuo. After recoverythe dried polymer was weighed and the activity is calculated.

EXAMPLE 2

A 205 mg sample of catalyst A prepared above in Example 1 was dryblended with 4 mg of Kemamine AS990 (available from Witco) and placed ina catalyst charge tube along with 2 mL of hexane then added to thereactor as described above. Polymerization was carried out as describedin Example 1. After one hour the polymerization was stopped. Inspectionof the reactor showed no fouling and free flowing, granular polymer. 234g of dried polymer was recovered equivalent to 1.14 Kg of polypropyleneper g of catalyst charged.

COMPARATIVE EXAMPLE 3

A 200 mg sample of the catalyst A used in Example 1 was used but withoutKemamine AS990. Polymerization was carried out as described inExample 1. After one hour the polymerization was stopped. Inspection ofthe reactor showed fouling on the stirring shaft and reactor walls. 232g of dried polymer was recovered equivalent to 1.16 Kg of polypropyleneper g of catalyst charged. Results are shown in Table 1.

EXAMPLE 4 and COMPARATIVE EXAMPLE 5

PREPARATION OF CATALYST B

A second prepolymerized catalyst (B) was prepared in an identical mannerto catalyst A. A 203 mg sample of prepolymerized catalyst B was testedfor propylene polymerization with and without Kemamine AS990.Polymerization was carried out as described in Example 1. Results areshown in Table 1.

COMPARATIVE EXAMPLE 6

This particular example illustrates adding the Kemamine AS990 to thecatalyst was unexpectedly better than adding it to the reactor. A 4 mgsample of the Kemamine AS990 was added to the reactor along withtriethylaluminum and propylene. A 200 mg sample of Catalyst A wascharged to the reactor with 250 ml of propylene to start the reaction.Polymerization was carried out as described in Example 1. Results areshown in Table 1.

                  TABLE 1                                                         ______________________________________                                                  Surface Modifier                                                                           Activity                                               Examples                                                                             Catalyst Wt %    Added to . . .                                                                         (Kg/g cat)                                                                            Fouled                               ______________________________________                                        2      A        2       Catalyst 1.14    No                                   Comp. 3                                                                              A        0       --       1.16    Yes                                  4      B        2       Catalyst 1.49    No                                   Comp. 5                                                                              B        0       --       1.53    Yes                                  Comp. 6                                                                              A        2       Reactor   0.375  Yes                                  ______________________________________                                    

In summary, the data shows that when dry blended with the catalyst ofthe invention, 2 wt % of a surface modifier, Kemamine AS990 eliminatedreactor fouling with little impact on catalyst activity. Where thesurface modifier is added to the reactor separately from the catalyst,fouling is not eliminated and catalyst activity is diminished by morethan 65%.

While the present invention has been described and illustrated byreference to particular embodiments, it will be appreciated by those ofordinary skill in the art that the invention lends itself to variationsnot necessarily illustrated herein. For this reason, then, referenceshould be made solely to the appended claims for purposes of determiningthe true scope of the present invention.

We claim:
 1. A method for producing a supported catalyst system, saidmethod comprising the steps of combining an alumoxane, a surfacemodifier, a porous carrier, and a metallocene catalyst component whereinthe surface modifier is represented by the formula: ##STR8## wherein R³is hydrogen or a branched or linear allyl group having 1 to 50 carbonatoms; R¹ is hydrogen or a branched or linear alkyl group having 1 to 50carbon atoms which may contain a heteroatom selected from O, N, P or S:and R² is (CH₂)_(x) OH wherein x is an integer from 1 to 50and whereinthe metallocene catalyst component is represented by the followingformula: ##STR9## wherein M¹ is a metal of group 4, 5, or 6 of thePeriodic Table, R¹ and R² are identical or different, are one of ahydrogen atom, a C₁ -C₁₀ alkyl group, a C₁ -C₁₀ alkoxy group, a C₆ -C₁₀aryl group, a C₆ -C₁₀ aryloxy group, a C₂ -C₁₀ alkenyl group, a C₇ -C₄₀arylalkyl group, a C₇ -C₄₀ alkylaryl group, a C₈ -C₄₀ arylalkenyl group,or a halogen atom; R³ and R⁴ are hydrogen atoms; R⁵ and R⁶ are identicalor different, preferably identical, are one of a halogen atom, a C₁ -C₁₀alkyl group, which may be halogenated, a C₆ -C₁ aryl group, which may behalogenated, a C₂ -C₁₀ aklenyl group, a C₇ -C₄₀ arylalkyl group, a C₇-C₄₀ alkylaryl group, a C₈ -C₄₀ arylalkenyl group, a --NR₂ ¹⁵, --SR¹⁵,--OR¹⁵, --OSiR₃ ¹⁵ or --PR₂ ¹⁵ radical, wherein R¹⁵ is one of a halogenatom, a C₁ -C₁₀ alkyl group, or a C₆ -C₁₀ aryl group; ##STR10## ═BR¹¹,═AlR¹¹, --Ge--, --Sn--, --O--, --S--, ═SO, ═SO₂, ═NR¹¹, ═CO, PR¹¹, or═P(O)R¹¹ ;wherein: R¹¹, R¹² and R¹³ are identical or different and are ahydrogen atom, a halogen atom, a C₁ -C₂₀ alkyl group, a C₁ -C₂₀fluoroalkyl group, a C₆ -C₃₀ aryl group, a C₆ -C₃₀ fluoroaryl group, aC₁ -C₂₀ alkoxy group, a C₂ -C₂₀ alkenyl group, a C₇ -C₄₀ arylalkylgroup, a C₈ -C₄₀ arylalkenyl group, C₇ -C₄₀ alkylaryl group, or R¹¹ andR¹², or R¹¹ and R¹³, together with the atoms binding them, can form ringsystems; M² is silicon, germanium or tin; R⁸ and R⁹ are identical ordifferent and have the meaning as stated for R¹¹ ; m and n are identicalor different and are zero, 1 or 2, m plus n being zero, 1 or 2; and theradicals R¹⁰ are identical or different and have the meanings stated forR¹¹, R¹² and R¹³ wherein further two adjacent R¹⁰ radicals can be joinedtogether to form a ring system.
 2. The method of claim 1 wherein thealumoxane and metallocene are contacted first in a solution which isthen combined with the porous carrier wherein the total volume of thesolution is less than about four times the total pore volume of theporous support.
 3. The method of claim 2 wherein the total volume of thesolution is less than about two times the total pore volume of theporous support.
 4. The method of claim 2 wherein the total volume of thesolution is from about 0.8 to about 3 times the total pore volume of theporous support.
 5. The method of claim 1 wherein the metallocenecatalyst component comprises two or more metallocene catalystcomponents.
 6. The method of claim 1 wherein the mole ratio of aluminumof the alumoxane to the transition metal of the metallocene catalystcomponent is in the range of between 20:1 to less than 500:1.
 7. Themethod of claim 2 wherein the solution is added to the porous support.8. The method of claim 1 further comprising the step of prepolymerizingthe supported catalyst system with an olefinic monomer.
 9. The method ofclaim 1 wherein m═n═0 and M² ═silicon.
 10. The method of claim 1 whereinR⁵ ═R⁶ ═C₁₋₁₀ alkyl.
 11. The method of claim 1 wherein three of the R¹⁰radicals═hydrogen and one is a C₆₋₃₀ aryl group.
 12. The method of claim1 wherein two adjacent R_¹⁰ radicals form a fused 4,5-benzo ring and theother two R¹⁰ radicals are hydrogen.
 13. The method of claim 1 whereinat least one of the R¹⁰ radicals is C₁₋₁₀ alkyl.
 14. The method of claim1 wherein the metallocene component is selected from the groupconsistingof:rac-dimethylsilandiylbis(2-methyl-4,5-benzoindenyl)-zirconiumdichloride, rac-dimethylsilandiylbis(2-methylindenyl)-zirconiumdichloride, racdimethylsilandiyl-bis(2-methyl-4,6-diisopropylindenyl)-zirconiumdichloride, rac-dimethylsilandiylbis(2-methyl-4-phenylindenyl)zirconiumdichloride, andrac-dimethylsilandiylbis(2-ethyl-4-phenylindenyl)zirconium dichloride.15. The method of claim 1 further comprising the step of drying thesupported catalyst system.
 16. The method of claim 1 wherein the surfacemodifier is present in an amount in the range of 0.2 weight percent toless than 5 weight percent of the total weight of the supported catalystsystem.
 17. The method of claim 1 wherein the surface modifier isrepresented by the formula: ##STR11## where R¹ is hydrogen or a linearor branched alkyl group of from 1 to 50 carbon atoms; R² is (CH₂)_(x) OHwherein x is an integer from 1 to
 50. 18. The method of claim 1 whereinthe surface modifier is selected from at least one of the group ofcompounds represented by the following chemical formula: C₁₈ H₃₇ N(CH₂CH₂ OH)₂, C₁₂ H₂₅ N(CH₂ CH₂ OH)₂ and (CH₃ (CH₂)₇ (CH)₂ (CH₂)₇ OCOCH₂(CHOH)₄ CH₂ OH.
 19. A method for producing a supported catalyst system,said catalyst system comprising a first component comprising a chiral,Group 4 transition metal, bridged, substituted bisindenyl metallocenecatalyst and a first solvent, a second component comprising an alumoxaneand a second solvent, and a porous support, said method comprising thestep of:a) combining the first component and the second component toform a reaction product solution; b) combining the reaction product andthe porous support, such that at any point during the formation of thesupported catalyst system the total volume of the reaction product addedto the porous support is less than four times the total pore volume ofthe porous support; and c) introducing a surface modifierwherein thesurface modifier is represented by the formula: ##STR12## wherein R³ ishydrogen or a branched or linear alkyl group having 1 to 50 carbonatoms; R¹ is hydrogen or a branched or linear alkyl group having 1 to 50carbon atoms which may contain a heteroatom selected from O, N, P or S;and R² is (CH₂)_(x) OH wherein x is an integer from 1 to
 50. 20. Themethod of claim 19 wherein the total volume of the reaction productsolution is less than about three times the total pore volume of theporous support.
 21. The method of claim 19 wherein the mole ratio ofaluminum of the alumoxane to the transition metal of the metallocenecatalyst is in the range of 20:1 to 500:1.
 22. The method of claim 19wherein the metallocene catalyst component is represented by the generalformula: ##STR13## wherein: M¹ is a metal of group 4, 5, or 6 of thePeriodic Table, R¹ and R² are identical or different, are one of ahydrogen atom, a C₁ -C₁₀ alkyl group, a C₁ -C₁₀ alkoxy group, a C₆ -C₁₀aryl group, a C₆ -C₁₀ aryloxy group, a C₂ -C₁₀ alkenyl group, a C₇ -C₄₀arylalkyl group, a C₇ -C₄₀ alkylaryl group, a C₈ -C₄₀ arylalkenyl group,or a halogen atom;R³ and R⁴ are hydrogen atoms; R⁵ and R⁶ are identicalor different, preferably identical, are one of a halogen atom, a C₁ -C₁₀alkyl group, which may be halogenated, a C₆ -C₁₀ aryl group, which maybe halogenated, a C₂ -C₁₀ alkenyl group, C₇ -C₄₀ arylalkyl group, a C₇-C₄₀ alkylaryl group, a C₈ -C₄₀ arylalkenyl group, a --NR₂ ¹⁵, --SR⁵,--OR¹⁵, --OSiR₃ ¹⁵ or --PR₂ ¹⁵ radical, wherein R¹⁵ is one of halogenatom, a C₁ -C₁₀ alkyl group, or a C₆ -C₁₀ aryl group; R⁷ is ##STR14##═BR¹¹, ═AlR¹¹, --Ge--, --Sn--, --O--, --S--, ═SO, ═SO₂, ═NR¹¹, ═CO,PR¹¹, or ═P(O)R¹¹ ;wherein: R¹¹, R¹² and R¹³ are identical or differentand are a hydrogen atom, a halogen atom, a C₁ -C₂₀ alkyl group, a C₁-C₂₀ fluoroalkyl group, a C₆ -C₃₀ aryl group, a C₆ -C₃₀ fluoroarylgroup, a C₁ -C₂₀ alkoxy group, a C₂ -C₂₀ alkenyl group, a C₇ -C₄₀arylalkyl group, a C₈ -C₄₀ arylalkenyl group, C₇ -C₄₀ alkylaryl group,or R¹¹ and R¹², or R¹¹ and R¹³, together with the atoms binding them,can form ring systems; M² is silicon, germanium or tin; R⁸ and R⁹ areidentical or different and have the meanings as stated for R¹¹ ; m and nare identical or different and are zero, 1 or 2 m plus n being zero, 1or 2; and the radicals R¹⁰ are identical or different and have themeanings stated for R¹¹, R¹² and R¹³ wherein further two adjacent R¹⁰radical; can be joined together to form a ring system.
 23. A process forpolymerizing propylene alone or in combination with one or more otherolefins, said process comprising polymerizing in the presence of asupported catalyst system of claim
 1. 24. A process for polymerizingpropylene alone or in combination with one or more other olefins, saidprocess comprising polymerizing in the presence of a supported catalystsystem of claim
 19. 25. A supported catalyst system produced by themethod of claim
 1. 26. A supported catalyst system produced by themethod of claim 19.